During energy industry operations, such as drilling, completion and stimulation (e.g., hydraulic fracturing), water-based fluids pumped into a borehole invade the surrounding formation and can cause fluid retention issues. Water block trapping is one of the major causes of damage after any treatment if the fluids remain in the pore space. Especially in hydraulic fracturing, the water blocks formed in the area surrounding the fracture and within the fracture have a detrimental effect on relative permeability and effective fracture lengths, thus reducing hydrocarbon permeability and well productivity. Over time, the hydrocarbon production rate may increase, but it can take many hours or up to a year to establish optimum production rate following fluid injection into the formation. In some cases, sensitive formations with very low permeability may never reach an economical producing rate.
Fracturing fluid trapping is one of the major sources of damage after well stimulation as the remaining fluids in the pore space reduce the effective hydrocarbon permeability. Especially in tight formations, fluid trapping can require significant time to clean up, even at a high production rate. Outcrop cores have traditionally been used to confirm the existence of damage and to quantify it. However, it is difficult to clearly discern the trapping mechanism in cores and to accurately determine the trapping location and the volume of residual fluid.